Geoservices plugins should be responsible for rendering the map and map objects

There is currently no public C++ mapping API. The existing private API (used by the QML Map type) has a number of subtle bugs which are hard to fix because the code that is rendering the map and map objects does not have all the required information.

The proposed API, as described by the header files in the attached api-suggestion.tar.gz file, addresses this by moving the rendering into the geoservices plugins.